Biogas how to deal with actual multi-input into a biogas plant. Horst Fehrenbach IFEU 23 October 2012, Heidelberg Greenhouse gas experts workshop

Transcription

1 Biogas how to deal with actual multi-input into a biogas plant Horst Fehrenbach IFEU 23 October 2012, Heidelberg Greenhouse gas experts workshop

2 Content What is the problem? What is ruled? Proposal for practical application conclusions Slide 2

3 What is the problem? Biogas plants are typically operating as multi-input Default values refer to single inputs. (exception: manure + maize, combined but separately calculated) For actual calculation: - biogas yield by input is basically relevant (MJ Biogas/MJ feedstock) - Actual biogas yields never match with literature values - Mixed feedstocks react unpredictably resulting from specific feedstock quality, fermenting conditions and technical factors (plant design, operation mode). Slide 3

4 What is the problem? BioGrace tool input value: specific single input WET MANURE: Anaerobic digestion Yield Biogas output 0,42 MJ Biogas / MJ Wet manure Energy consumption Electricity EU mix LV Heat (from biogas CHP) Biogas CHP Biogas input per MJ heat 0,019 MJ / MJ Biogas 0,096 MJ / MJ Biogas 0,101 MJ / MJ Heat Slide 4

5 What is the problem? BioGrace tool input value: specific single input MAIZE Anaerobic digestion Yield Biogas output 0,60 MJ Biogas / MJ maize Energy consumption Electricity EU mix LV Heat (from biogas CHP) Biogas CHP Biogas input per MJ heat 0,024 MJ / MJ Biogas 0,098 MJ / MJ Biogas 0,101 MJ / MJ Heat Slide 5

6 What is the problem? Feedstock 1 e ec 1 Feedstock 2 e ec 2 Feedstock 3 e ec 3 Biogas plant e p Biogas E = e ec + e p Slide 6

7 What is ruled? Communication from the Commission on voluntary schemes and default values in the EU biofuels and bioliquids sustainability scheme (2010/C 160/01): mass balance: When consignments with different (or no) sustainability characteristics are mixed, the separate sizes and sustainability characteristics of each consignment remain assigned to the mixture 8. 8 Thus, if the characteristics include different figures on greenhouse gas emissions they remain separate; these figures cannot be averaged for the purpose of showing compliance with the sustainability requirements. Slide 7

8 What is ruled? Feedstock 1 e ec 1 Feedstock 2 e ec 2 Feedstock 3 e ec 3 Biogas plant e p AF1 e p AF2 e p AF3 Biogas E1 = e ec 1 + e p AF1 Biogas E2 = e ec 2 + e p AF2 Biogas E3 = e ec 3 + e p AF3 Slide 8

9 What is needed for actual calculation? Feedstock 1 e ec 1 Biogas plant e p AF1 e p AF2 e p AF3 Biogas E1 = e ec 1 + e p AF1 Operators Feedstock can 2 measure Feedstock the total 3 biogas e ec yield 2 related to the e ec total 3 input of all feedstocks. Nobody can measure which portion of biogas is actually originated from which feedstock. Standardized factors are needed to derive the portions of biogas to be separately assigned to each of the Biogas different inputs. E2 = e ec 2 + e p AF2 Biogas E3 = e ec 3 + e p AF3 Slide 9

10 Proposal for practical application Slide 10 Take standardized factors describing biogas yield ratios by feedstock. - e.g. from KTBL 2009: Faustzahlen Biogas feedstock Biogas Yield l/kg dry org. matter CH4 content % CH4 yield l/kg dry org. matter grown biomass CCM Futterrübensilage Getreide-GPS Getreidekorn Grassilage Grünroggensilage Kartoffeln mittl. Stärkegehält Klee-/Luzernesilage Kleegrassilage Körnermais Landschaftspflegegras Maissilage Raps ,2 356 Sonnenblumensilage Sorghumsilage Stroh Sudangras ,7 257 Topinambur Weidelgras Weißkohlblätter Zuckerhirse Zuckerrübensilage manure Geflügelmist Pferdekot Rindermist Rindergülle Schafmist ,5 Schweinegülle

11 Proposal for practical application Take standardized factors describing biogas yield ratios by feedstock. Apply these factors to assign the actual total biogas volume to the separate feedstock quantities. - e.g.: 40 m 3 Biogas (= MJ) generated from: 180 t maize, 50 t wheat whole plant, 150 t wet manure. Input Input energy value yield factor theoretical biogas yield actual biogas yield assigned biogas portion adapted yield factor t (f.m.) t (d.m.) MJ (d.m.) MJ bg/mj fs MJ MJ (m3) MJ MJ bg/mj fs Maize silage ,6 1036,8 0, ,1 695,5 0,671 wheat whole plan , ,5 234,8 0,652 wet manure , ,401 90,2 94,8 0,421 Sum 1621,8 975, ,0 (40 m3) Measured by operator Slide 11 Applied to the BioGrace spreadsheet

12 Proposal for practical application BioGrace tool input value: Actual value for specific input in input mixtures MAIZE Anaerobic digestion Yield Biogas output 0,671 0,60 MJ Biogas / MJ maize Energy consumption Electricity EU mix LV Heat (from biogas CHP) Biogas CHP Biogas input per MJ heat 0,024 MJ / MJ Biogas 0,098 MJ / MJ Biogas 0,101 MJ / MJ Heat Slide 12

13 Proposal for practical application Need to implement such an approach as a calculation rule? Prevent cherry-picking! Feedstock 1 Feedstock 2 Feedstock 3 Biogas plant Biogas Biogas Biogas Slide 13 Assigning low GHG emissions arbitrarily to this portion. Assigning the major part of GHG emissions arbitrarily to other portion.

14 Conclusion In Germany operators from biogas plants, of certification system and verifiers require a valid and recognized scheme to handle multi-input feedstocks into biogas plants. The proposed approach just clarifies the way how to assign actual feedstock input to actual biogas output mass balance of process is unaffected! Data and approach should be handled as a rule similarly to the BioGrace calculation rules because otherwise there some space left open for cherry-picking. Slide 14